Abyssal is one of the few entirely original languages in Archaeron, devised by some ancient power for the less benign metaspirits. They have spoken it, essentially unmodified, throughout history. Whoever crafted this language, they made it to be terrible and frightening. Abyssal is often used in the more obscure books of ritual. Because it was developed for extraplanar creatures, it excels at describing geometric and arcane anomalies that other languages struggle with.